As a technology for performing coarse adjustment to a formation position of a correction patch group related to image forming, related art (for example, JP-A-2009-069767) discloses accurately detecting a correction toner image by a first correction mark group for correcting positional misalignment (a second adjustment image). The first correction mark group is configured of marks parallel with a main scanning direction, which is an image read direction in image forming (a direction perpendicular to a conveyance direction of an image formation sheet), and marks inclined with respect to the main scanning direction. In this case, a size of a patch group for correcting positional misalignment of an image (a first adjustment image) is reduced, so as to reduce consumption of a developer. The term “coarse adjustment” means adjusting the formation position of a patch group such that the patch group is formed on a light projection line of a patch detection sensor, prior to adjusting of an image that is performed based on a patch-group detection result of the patch detection sensor.